Centrifugal engine

ABSTRACT

A novel kind of propulsion system that uses centrifugal force to accelerate the surrounding work-fluid. A rotor ( 10 ) with radially mounted blades ( 11 ) is enclosed by a cylindrical enclosure ( 12 ). The cylinder wall of the enclosure ( 12 ) is partially open to the surrounding work fluid. The rotor is rotated in the housing and surrounding fluid thereby generating the propulsive force.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of German Patent Application Number 102005005142.1 entitled “Zentrifugalarbeitsmaschine”, filed Feb. 02, 2005, in Germany by the present inventors. The above priority application is hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of Invention

This invention relates to marine and aeronautic propulsion systems, specifically a propulsion system that can replace a conventional propeller.

All known marine and aeronautic propulsion systems share the common working principle in that the work fluid flows through the engine. This is true for propellers, jets, turbines, and water wheels. EP-1355822 describes a water wheel with sprockets that move the work fluid through an enclosure using a rotor. The sprockets move the surrounding water into a canal within the engine. This water stream gets accelerated in the engine and expelled to generate the propulsion. These are in stark contrast to the working principle of the Centrifugal Engine disclosed here. The Centrifugal Engine generates the propulsion with little or no work fluid exchange between engine and environment.

Not much has changed in terms of the overall principle since the basic design was discovered. The basic principle of a propeller is to accelerate the fluid in front of the propeller and therefore generate a force on the propeller blades in the opposite direction. This force is usually used to propel a ship vessel or aircraft. The main idea is that the work fluid (water or air) flows through the propeller while the propeller blades transfer energy to the surrounding fluid. There are numerous variations of the same concept like water wheels, turbines, and jet engines. In each case the work fluid flows through the propulsion system. Although very simple in its design the propeller has some disadvantages. To transmit large amounts of power either the rotational speed of the propeller blades or their surface area need to be increased. This increase leads to an increase of the velocity at the circumference of the propeller and can cause an effect called cavitation in which the propeller loses touch with the water.

Cavitation is the formation and collapse of low-pressure bubbles on the propeller blade surface and causes damage to the propeller. Propellers also cause turbulences in the work fluid due to the fluid passing through the propeller which also produces acoustic emissions. All these effects lead to a maximum theoretical propeller efficiency of about 70%. In practice this number is rarely realized. A more efficient means of propulsion as achieved by the Centrifugal Engine is desired.

Compared to common fluid-flow engines the Centrifugal Engine according to this invention has the following advantages:

-   a) Significant energy savings can be accomplished due to a new means     of propulsion with less friction losses. -   b) It is less prone to cavitation than conventional propulsion     systems. -   c) It is possible to achieve higher energy throughput which in turn     allows a smaller form factor compared to known solutions. -   d) The maximum transferable energy of the Centrifugal Engine depends     on the pressure of the surrounding fluid. This results in higher     transferable energies in larger depths which is advantageous for     submarines. -   e) The propulsion does not generate a turbulent fluid-flow and is     therefore less noisy than conventional mechanisms and has advantages     in fishing, surveillance, military, and science. -   f) Through the enclosure of the rotor the propulsion system is not     exposed and has advantages in personal watercraft where an exposed     propeller would present significant risk of personal injury. The     Centrifugal Engine presents significantly less risk of personal     injury.

SUMMARY OF THE INVENTION

The Centrifugal Engine described hereby utilizes an entirely new method of propulsion. The work fluid does not pass through the Centrifugal Engine like through a conventional fluid-flow engine. Fluid-flow engines like centrifugal pumps, propellers, and jets are well known. These conventional fluid-flow engines use blades which are flowed through by the work fluid to transfer energy. The friction losses caused by this throughput of the fluid through the engine limit the maximum theoretical efficiency. The Centrifugal Engine accomplishes the transfer of energy from the rotor to the work-fluid without a throughput of work-fluid through the engine.

The Centrifugal Engine causes less turbulence and less acoustic emissions making it advantageous in scientific or military applications for submarines. The friction losses are minimized compared to conventional fluid-flow systems since the work fluid does not pass through the engine but is merely accelerated by a low pressure field. Therefore the Centrifugal Engine operates more efficiently than currently known solutions in marine propulsion.

The Centrifugal Engine accomplishes this by creating a low pressure field in a rotor that is partially enclosed by a cylindrical enclosure. The low pressure field creates a binding between the rotor and the work fluid in the environment similar to the traction between a tire and the road. The clearances between rotor and enclosure are kept as small as possible to avoid any work fluid being transported through the engine. This is in stark contrast to patent EP-1355822 where a gap between the rotor and enclosure provides a canal for a water stream to be transported through the engine. This essentially is the principle of a water wheel. The Centrifugal Engine uses a different means of propulsion that works without work fluid being transported through the engine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a shows the Centrifugal Engine in a vertical mount position on the rear of a watercraft.

FIG. 1 b is a cross-sectional view of the vertically mounted Centrifugal Engine shown in FIG. 1 a along a plane perpendicular to the rotor axis.

FIG. 2 shows a cross-sectional view of an alternative embodiment of the Centrifugal Engine with integrated electrical motor.

FIG. 3 shows a cross-sectional view of an alternative embodiment of the Centrifugal Engine with porous rotor material replacing the cells formed by rotor blades.

FIG. 4 a shows a side view of the Centrifugal Engine in an alternative embodiment with two counter-rotating rotors in a horizontal mount position on the rear of a watercraft.

FIG. 4 b shows a cross-sectional view of the Centrifugal Engine from FIG. 4 a, looking downward and taken about the line 4 b-4 b of FIG. 4 a.

FIG. 5 a shows the Centrifugal Engine integrated into a vessel body.

FIG. 5 b shows a cross-sectional view of the Centrifugal Engine mounted into a vessel body shown in FIG. 5 a, looking rearward and taken about the line 5 b-5 b of FIG. 5 a.

FIG. 6 illustrates the fluid flow in the proximity of the Centrifugal Engine.

FIG. 7 a, b, c show various views of the Centrifugal Engine mounted to an outboard motor.

LIST OF REFERENCE NUMERALS

-   10 Rotor with blades -   11 Rotor blades -   12 Rotor enclosure -   13 Vessel Hull -   14 Connecting rod -   15 Mounting bracket for vertical mount

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

FIG. 1 a shows a side view of the Centrifugal Engine mounted to the rear of a vessel. Referring additionally to FIG. 1 b, an apparatus in accordance with the invention comprises a rotor shaft, a rotor 10, and a cylindrical rotor enclosure 12. The rotor is mounted to the rotor shaft and consists of a hub with radially mounted blades 11. The rotor 10 is enclosed by a cylindrical enclosure 12 in such a manner that the rotor 10 can freely spin in the enclosure 12. The rotor blades 11 form cells with the surrounding enclosure. The enclosure 12 is constructed in such a way that the rotor exposes some cells to the working fluid. The top and bottom of the rotor 10 as well as a portion of the side walls is covered by the cylindrical enclosure 12. The clearances between the rotor blades and the enclosure are kept as small as technical possible to avoid work fluid being transported through the engine. The rotor shaft that is mounted to the rotor in a fixed manner passes through the enclosure and is attached to the enclosure with bearings (not shown) and water tight seals (not shown) so that the only contact of the rotor with the surrounding work fluid happens at the opening of the enclosure 12. The top and bottom of the enclosures 12 are sealed against the exchange of work fluid. FIG. 1 b shows a cross sectional view of the Centrifugal Engine displayed in FIG. 1 a about the line 1 b-ib.

The rotor 10 is driven by a motor 16. In the illustrated embodiment motor 16 is an electric motor mounted within the rotor. In one preferred embodiment rotor 10 is mounted on rotor 18 of motor 16. In other embodiments, rotor 10 could be driven by an engine or motor mounted in the hull vessel and connected to motor 16 by cable, shaft, gear box, or any other suitable drive transmission mechanism known to those of skill in the art. In yet other embodiments rotor 10 could be driven by a gear drive mechanism located within rotor 10.

Operation of Invention

The enclosure 12 is fully submerged into the work fluid. When a rotational force is applied to the rotor shaft, the rotor blades 11 accelerate the fluid in the rotor cells which results in a centrifugal force on the work-fluid contained in the cells. Since water is incompressible it can not leave the cells since they are closed and no surrounding fluid can enter the cells. The centrifugal force results in a lowering of the pressure of the work-fluid in the cell areas relative to the surrounding work fluid. Due to the difference in cell pressure and surrounding pressure the surrounding fluid is accelerated toward the rotor 10. The rotor 10 acts like a vacuum sucking in the surrounding fluid. This suction occurs in the area where the rotor 10 is exposed by the enclosure 12. The surrounding fluid which is accelerated towards the enclosure 12 is redirected onto a tangential path around the rotor 10 in the proximity of the enclosure 12. The fluid moving on a tangential path along the rotor 10 is separated from the rotor at the point where the enclosure wall starts. The enclosure wall separates the rotor cells from the surrounding fluid and the accelerated fluid in the proximity of the enclosure will divert tangentially.

The preferred mount position is vertically (the rotor plane is vertical) as shown in FIG. 1 a. The Centrifugal Engine is preferably connected to the vessel hull 13 through a connecting rod 15 that can optionally pivot the engine to achieve varying directions of propulsion.

Alternative Embodiments

In the preferred embodiment as outlined above the rotor cells are formed between the rotor hub, the rotor blades 11 and the enclosure 12. An alternative embodiment is to replace the rotor blades by a porous material as illustrated in FIG. 3. The basic principle of the Centrifugal Engine is to create a low pressure field within the rotor cells which attracts the surrounding fluid. Such a pressure field will be created equally in a rotor consisting of a porous material that holds work-fluid.

A porous rotor is disclosed in U.S. Pat. No. 5,297,942. In this prior art the propulsion is generated by the work fluid flowing through the rotor as in conventional propulsion mechanisms like pumps, propellers, jets, and water wheels. The Centrifugal Engine uses the porous rotor only to build a pressure difference between the work fluid in the rotor cells and the environment.

Another alternative embodiment is depicted in FIG. 4 a. For symmetry reasons this alternative embodiment consists of two counter-rotating rotors. The cross-sectional view in FIG. 4 b illustrates the configuration of the two rotors. In this configuration the Centrifugal Engine can be mounted horizontally, that is with the rotor plane oriented horizontally.

FIG. 2 shows an alternative embodiment where the motor is built in the rotor which leads to a very compact construction. Integrated marine propulsion systems like pod drives are well known. Instead of driving a jet drive or propeller, this alternative embodiment utilizes an integrated electrical motor to drive the Centrifugal Engine.

A further alternative embodiment is the Centrifugal Engine with parts of the opening covered with a membrane. The membrane will not let work fluid pass through but still causes the pressure difference to attract the surrounding work fluid causing the appropriate traction.

Theory of Operation

We believe the Centrifugal Engine has such different characteristics from common fluid-flow engines because it is based on a different working principle. The low pressure field in the rotor attracts the surrounding fluid, binding it to the rotor. This can be compared to the traction of a tire on a road surface. The more traction the tire has the more energy can be transferred. The Centrifugal Engine creates this traction between the rotor and the surrounding fluid within the laminar boundary layer along the rotor. FIG. 6 illustrates the fluid flow in the proximity of the Centrifugal Engine. In the stationary case with the Centrifugal Engine mounted in a fixed position the work fluid is moved along the engine. However, when the Centrifugal Engine is in motion relative to the surrounding work fluid the differential velocity between the rotor and the work fluid will be minimized and only a small difference in velocity will remain. This is comparable to propeller slip. The higher the traction generated by the Centrifugal Engine the smaller this difference in velocity will be and the more energy can be transferred to the work fluid.

While we believe the Centrifugal Engine to function in the way stated above we don't wish to be bound by this.

Scope of Invention

While the Centrifugal Engine has been described in reference to a specific embodiment, in light of the foregoing, it should be understood that all matter contained in the above description or shown in the accompanying drawings is intended to be interpreted as illustrative and not in a limiting sense and that various modifications and variations of the Centrifugal Engine may be constructed without departing from the scope of the invention defined by the following claims. For example, it should be appreciated that the rotor enclosure can be pivoted around the rotor axis to achieve different directions of propulsion. Additionally, it should be appreciated that the rotor cells may be formed from porous material instead of radially mounted rotor blades. Moreover, the optimum dimensions of the rotor and rotation frequency may vary based on the particular configuration of the propulsion assembly and on the application like tug boat, speed boat, personal watercraft, etc. Thus, other possible variations and modifications should be appreciated.

Furthermore, it should be understood that when introducing elements of the Centrifugal Engine in the claims or in the above description of the preferred embodiment of the Centrifugal Engine, the terms “comprising”, “including”, and “having” are intended to be open-ended and mean that there may be additional elements other than the listed elements. Similarly, the term “portion” should be construed as meaning some or all of the item or element that it qualifies. 

1. A propulsion system for propelling a vessel in a fluid comprising: a vessel; a housing mounted on the vessel and immersed in an underlying fluid, and having a concave portion; a rotor having a plurality of blades extending from the periphery of the rotor, the rotor mounted to the housing and having a rear peripheral portion positioned adjacent the concave portion of the housing; and, the system operable to rotate the rotor thereby generating a propulsive force to propel the vessel through the fluid.
 2. A propulsion system according to claim 1 further comprising each blade having a distal portion angled toward the direction of rotation of the rotor.
 3. A propulsion system according to claim 1 further comprising each blade being curved and having a distal portion angled toward the direction of rotation of the rotor.
 4. A propulsion system according to claim 1 operatively mounted on a vessel.
 5. A propulsion system according to claim 1 operatively mounted on a vessel and rotationally relative to the vessel.
 6. A propulsion system according to claim 5 operable to apply a propulsive force to the vessel in a plurality of directions.
 7. A propulsion system according to claim 6 rotationally mounted on a vessel and operable to apply a propulsive force to the vessel in a plurality of directions.
 8. A propulsion system according to claim 1 further comprising a motor operatively connected to the rotor.
 9. A propulsion system according to claim 8 wherein the motor is selected from the group consisting of an electric motor, a hydraulic motor, a steam motor, an internal combustion motor, and a turbine.
 10. A propulsion system for generating a propulsive force in a fluid comprising: a housing having at least first and second concave portions; first and second rotors having respective rear peripheral portions positioned adjacent the respective first and second concave portions of the housing, and also having respective first and second pluralities of blades extending from the respective peripheries of the first and second rotors; and, the first and second rotors operable in a fluid to rotate the respective pluralities of blades past the respective concave portions of the housing thereby generating at least one propulsive force acting to drive the propulsion system through the fluid.
 11. A propulsion system according to claim 10 further comprising each blade having a distal portion angled toward the direction of rotation of the rotor.
 12. A propulsion system according to claim 10 further comprising each blade being curved and having a distal portion angled toward the direction of rotation of the rotor.
 13. A propulsion system according to claim 10 operatively mounted on a vessel.
 14. A propulsion system according to claim 10 operatively mounted on a vessel and rotationally relative to the vessel.
 15. A propulsion system according to claim 14 operable to apply a propulsive force to the vessel in a plurality of directions.
 16. A propulsion system according to claim 15 rotationally mounted on a vessel and operable to apply a propulsive force to the vessel in a plurality of directions.
 17. A propulsion system according to claim 10 further comprising a motor operatively connected to each rotor.
 18. A propulsion system according to claim 17 wherein each motor is selected from the group consisting of an electric motor, a hydraulic motor, a steam motor, an internal combustion motor, and a turbine.
 19. A propulsion system according to claim 1 wherein the rotor mounted to the housing and having a rear peripheral portion positioned adjacent the concave portion of the housing includes a clearance between the rear peripheral portion and the concave portion is selected to be the minimum required to provide clearance between the rotor and the housing. 